Drills using rotatable bits for penetrating into the earth are in widespread use. One application of such drills is in conjunction with a machine known in the vernacular as a “roof bolter” capable of both forming boreholes in the faces of the passageways of underground mines and then installing roof anchors or “bolts” in the boreholes. As is well-known in the art, the bolts once installed provide support for the adjacent portion of the mine face (typically the roof and ribs), thereby reducing the incidence of catastrophic cave-ins.
In the typical bolting operation, once the borehole is created using the drill, a resin cartridge is inserted. The drill head is then used to insert a roof bolt into the borehole to rupture the resin cartridge. Once ruptured, the bolt is rotated using the drill head to mix the resin, which is designed to quickly set and form a secure bond with the material surrounding the borehole.
Oftentimes, a manual operator input device, such as a joystick, is used to control the operation of the drill head, both during the drilling and bolting cycles of the operation. A single joystick may be associated with a manual control valve such that movement in a first direction (i.e., forward) results in drill head feed, rotation, or both. Alternatively, two independent joysticks may be used: one for controlling feed and the other, rotation. Using a manual control valve also allows the speed and direction of rotation or feed to be easily controlled by simply pivoting the joystick. However, electronic, solenoid-operated proportional control valves may also be used, if desired.
While an input device such as a joystick provides an intuitive and easy-to-use interface for controlling the drilling and bolt insertion operations, it has been discovered that the operator sometimes inadvertently moves the input device (joystick) for causing rotation when only feed is desired. Likewise, the operator may desire to rotate the chuck at a slow speed to assist in coupling the bolt head with a wrench or socket in a drill “pot,” but inadvertently move the joystick to a position such that a higher rotational speed results. Both of these occurrences essentially require the operator to repeat the procedure and, consequently, decrease the efficiency of the operation.
Accordingly, a need is identified for a manual input device or system for use in controlling a drilling operation, such as during the forming boreholes in one or more faces of a passageway in an underground mine. The input device would be simple to operate using only one hand, yet would prevent inadvertent actuation of the drill head (feed, rotation, or both). The input device would provide failsafe operation and would be tamper-resistant to prevent operator override. The input device would also be easily retrofitted onto existing drilling machines. The use of a neutral switch to prevent movement (tramming) of a drilling machine on power up is also disclosed.